/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/Collision/PBDCollisionConstraintHandle.h
This is an intrusive handle, so you can use a contact pointer as a handle.
class FPBDCollisionConstraintHandle : public [Chaos::TIntrusiveConstraintHandle< FPBDCollisionConstraint >](API\Runtime\Chaos\Chaos\TIntrusiveConstraintHandle)